The present invention generally relates to electrical machinery and more particularly, to a rotary electrical machine in which a reduction gear or reduction mechanism section is formed in one unit with a motor section.
As shown in FIG. 1, a conventional electrical rotary machine includes, for example, a reduction mechanism section A having gears 13, 15, 17, 20, etc. accommodated in a chamber constituted by a gear case 1 and a lid portion 2, and a motor section B having a rotary driving portion housed in another chamber formed by a motor case 3 and a lid portion 4. For assembly, the reduction mechanism section A and motor section B separately constituted are combined and to each other by screws 24 and the like. A rotor 6 having pole teeth and disposed to confront a magnetized face of a circular permanent magnet member 5 secured to the lid portion 4, is fixed to a rotor shaft 8 through a rotor boss portion 7. Within the motor case 3, there are fixedly disposed a coil bobbin 11 having a coil 23 wound therearound, a yoke member 10, and a rotor bearing 9 in which the rotor shaft 8 is rotatably fitted. The rotor bearing 9 is in contact with the gear 13 secured to the rotary shaft 8 through balls 12 provided at one end portion of said rotor bearing 9. Accordingly, the rotation of the gear 13 is transmitted to an external appliance (not shown) via the gear 15, supported by a shaft 14, gear 17 supported by a shaft 16 which are provided in the gear case 1, and gears 20 and 22, etc. respectively supported by a shaft 19 mounted on the case 1 and lid portion 2 in bearings 18 and 21.
In the conventional rotary machine as described above, since the reduction mechanism section A and motor section B are separate elements combined into one unit by screws and the like as described earlier, it has been unavoidable that the number of parts, time required for the assembly, manufacturing cost, etc., are undesirably increased.